In the field of clinical examinations, blood is routinely collected from a body and used as a sample which is measured by a sample analyzer to aid diagnosis and monitor treatment. Furthermore, body fluids other than blood are also often used as samples which are measured by a sample analyzer. The body fluids are usually transparent and contain very few cells, however, cells such as bacteria, abnormal cells, and hemorrhage (blood cells) and the like may be found in cases of disease, tumors of related organs, and injury.
When cerebrospinal fluid, which is one type of body fluid, is measured, for example, it is possible to make the following estimations from the measurement results.                Increase of red blood cells: subarachnoidal hemorrhage        Increase of neutrophils: meningitis        Increase of eosinophils: infectious disease (parasites and fungus)        Increase of monocytes: tuberculous meningitis, viral meningitis        Other cells: advanced meningeal tumor        
Japanese Laid-Open Patent Publication No. 2003-344393 discloses a blood cell analyzer which is capable of measuring cells in a body fluid. In Japanese Laid-Open Patent Publication No. 2003-344393, an operator prepares a measurement sample prior to performing the measurements by mixing a fluid sample and reagent (aldehyde, surface active agent, and cyclodextrin) in order to stably store the body fluid for a long period, and this measurement sample is later subjected to fluid analysis by the sample analyzer.
In the art of Japanese Laid-Open Patent Publication No. 2003-344393, however, the measurement sample is not prepared by the sample analyzer when the body fluid is measured, rather the measurement sample must be prepared by the operator of the analyzer. Furthermore, the sample analyzer disclosed in Japanese Laid-Open Patent Publication No. 2003-344393 does not disclose measurement operations suited to the fluid when measuring a body fluid.